For some reason Viator booked this tour with another agent in Cairo besides the one we had for all our other tours. When we discovered this we phoned Viator long distance from Cairo. They said there was nothing that could be done and we would forfeit our fee if we cancelled then. We decided to go ahead.
They arrived at our hotel on time and in a clean vehicle. I hate to speak ill of a tour operator but I feel others should know what they are getting into. The company was Pyramid Tours if I recall correctly. The guide spoke limited English and was very young. It appeared that his pitch was rehearsed and not easy to understand. When we asked questions which I admit we do a lot he wasn't able to respond cogently. It became tedious enough that we cut the tour short before lunch after seeing only two venues. We went back to our hotel, had a nice lunch and set out on our own walking tour of Zamalek.
I relaize the guide certainly did his best and tried very hard. He was a nice guy but the tour operator should have known his limitations. It was not an inexpensive tour by any means.
I suggest you investigate who the local operator is when you first book as Viator uses multiple agents in each market.
Over all disappointing but if you are going to have a problem in traveling, it was a pretty minor problem in an overall great trip.